1. Field of the Invention
The present invention relates generally to implantable medical devices, and more particularly to, a housing for an implantable medical device.
2. Related Art
Devices are implanted in the body of a recipient for a variety of purposes including monitoring, heart defibrillation, drug delivery and as neural and organ prostheses. Such implantable devices generally include electronic components and other functional elements configured for a variety of purposes, including delivery of electrical stimulation or drugs, monitoring of parameters, communication with, or control of, other devices to store information, and communication via RF or other means.
Housing assemblies for implantable devices are required to be hermetically sealed and impervious to bodily fluids. This protects the recipient from any interactions with non-biocompatible materials used in the construction of the components housed inside the housing assembly, and from other adverse interactions with the sealed components. The housing also protects the functional components of the device from bodily fluids which could cause electrical short-circuits or otherwise lead to failure of the device.
Certain devices require one or more electrical connections between the interior of a device housing and elements exterior to the device housing. Hermetic enclosures for such devices are constructed from biocompatible materials, such as titanium or ceramic, and include a feed-through component. The function of the feed-through is to provide an electrically conductive path from inside the enclosure to outside the enclosure, typically for several separate conductors. If the housing is formed from titanium (or other conductive material), the conductors need to be insulated from the housing, as well as from each other. The feed-through also needs to maintain a hermetic enclosure while passing through the housing body. The feed-through is typically constructed from platinum conductors embedded in a ceramic carrier.
Conventional assembly of the hermetic enclosure to encase the electronics for traditional implant designs requires significant skilled labor input and numerous operations. Housings are currently typically made from multiple pieces and require the device to be inverted to facilitate connections. Such complex assembly is costly and does not facilitate automation and reliability within the assembly process.
For example, patent document WO 2006/081361 discloses an implantable medical device having a top and bottom shell, between which is enclosed a chassis. The chassis has functional components secured to it and is hermetically sealed to one of the shells. The chassis has a feed-through allowing input and output lines to pass into or out of the hermetic enclosure.
Furthermore, U.S. Pat. No. 6,011,993 discloses an implantable medical device made from an electronic subassembly hermetically sealed in a ceramic case filled with a potting material. The case is hollow with a closed end and an open end through which the electronic subassembly is inserted while the potting material in the case is still non-cured or in a quasi-fluid state. A header, to which the electronic subassembly is connected, is hermetically bonded to a band on the open end of the case thus hermetically sealing the medical device. The header has a plurality of electrical feed-through terminals for connecting to the electronic components on the subassembly. A particular disadvantage of such a device is the complex, highly skilled assembly required for its manufacture.
Additionally, U.S. Pat. No. 4,785,827 discloses a housing assembly for electronic circuitry that can be used subcutaneously. The housing comprises a container and base subassemblies each including a ceramic portion and a continuous metal sealing flange. The ceramic portion of the container subassembly is dish like and contains a cavity within which are housed electronic components. A plurality of electric leads are brazed to and extend from the container subassembly. The sealing flanges of the container and base subassemblies are then nested together and welded to close and seal the housing assembly. This assembly requires complex skilled assembly.